You've probably heard of his elder brother. Eric Gill was a sculptor (see 55 Broadway) and typeface designer (see Gill Sans), with a distinctly questionable private life. MacDonald Gill took a livelier look at life, making his name as a graphic artist with a particular penchant for painted maps. An exhibition of his work has been underway for the last six weeks in Ealing in the gallery at Pitzhanger Manor and, sorry, it was well worth a visit. Gill's fledgling skills were spotted by Frank Pick, London Underground's great design coordinator, who asked him to create a light-hearted map of the system to display as a poster. The result was the 'Wonderground' map, a triumph of cartoon cartography, which captured the hearts of the capital's travellers in 1914. They stopped and stared at the intricacies and characters on within, from Camden to Clapham and from Hammersmith to Hackney, and thousands bought their own copy for six shillings. It's still a treat to scrutinise the map today, spotting the puns and poems and stations long since closed. Further maps of Theatreland and Country Bus Routes ensued, each equally engaging and eminently covetable. You can forget Google Maps - MacDonald's coloured charts have far more 3D charm, and often far more useful information.

At the end of the war Gill was commissioned to design the typeface used on standard military gravestones, hence his work can be seen across countless cemeteries in France and Flanders. The exhibition also included several maps of the Empire, with large parts painted red of course, to highlight themes such as Post Office Communications, shipping lanes and tea. The International Tea Market Expansion Board commissioned several pieces, with one - Tea Revives the World - appropriated as part of the war effort in 1940. One of his largest works was for the first class lounge on the Queen Mary, a figurative map depicting a transatlantic crossing. We enjoyed all of these, and more, those of us who trotted along to Ealing on the last day of the exhibition. And you can't, because it's closed. But you can click through a detailed guide to the exhibition's first appearance, in Brighton in 2011, which ought to give you all the graphic backstory you could want. Alternatively there's a 40 minute podcast biography to enjoy here. And if you're particularly smitten you can buysome of Gill's maps, including the marvellous Wonderground. It would be fantastic to see it again adorning platforms next year to celebrate its centenary... what say you TfL?

WarrenElsmore never grew out of playing with Lego. Not the skewiff blocky houses that most of us spent our childhoods creating, but proper recognisable buildings, and on a grand scale. He's done a lot of London landmarks, and he specialises in 3D commissions for corporations, campaigns and whatever. I was immensely impressed by his Olympic Park last year, which you can see under construction here and in its final full glory here. Warren's compiled many of his favourites into a book, entitled Brick City. It's been out for a while, but various models from within are currently on tour and have spent the last week in the artsdepot in Finchley. I had to fight past an uber-worthy street theatre company singing some eco-message on carts in the road outside, which wasn't pleasant, but thankfully the gallery inside (and upstairs) was rather quieter. Centrepiece was a massive St Pancras built from sixty thousand plastic bricks, with the proper gothic hotel up front and the full set of platforms out back. Some of the Eurostars looked like they were toppling off the track, but the attention to detail was impressive, even down to a behatted Betjeman in plastic staring up at the roof.

I was expecting more, but only a small number of additional models surrounded the big station. A Buckingham Palace balcony complete with waving royals for one, and a Battersea Power Station (plus flying pig) for another. Heading abroad there was a Reichstag and a Colosseum, the latter a fine example of how it doesn't take too many bricks to create a convincing reproduction. The exhibition attracted Lego lovers of all ages, from three old ladies who followed me off the number 82 bus to a couple of hairy, animated students. One fan, who must have been all of two years old, stepped forward to rearrange the characters on the St Pancras hotel forecourt somewhat destructively. His mum held him back and gave him a talking to, to no avail because he was straight back in there stepping enthusiastically through the barrier. Thankfully he was swiftly distracted by the opportunity to play with some ordinary non-landmark Lego in the corner of the gallery, and further damage was averted. Had we been there earlier we could have met Warren himself, who was present to sign some books and smile. But you're too late... unless you're in Paisley over the winter, or in Newcastle next Spring. Sometimes the most interesting exhibitions are to be found where you'd least likely look.